I have a Microsoft Windows based network at the office and they've setup a VPN connection for me to be able to hook up to the servers to take care of a couple of ASP.NET applications and manage the server.
Ever since I installed Ubuntu 8.10, I've been a bit disconnected from the office as I can only access the services exposed by the web gateway, so I finally decided to setup a VPN connection from Linux.
I started off by clicking on the network icon on the top-right of the menu bar and then Configure VPN (under VPN Connections). The VPN tab had the Add button disabled so I went to the command prompt (Application, Accessories, Terminal) and typed the following command:
sudo apt-get -y install network-manager-pptp
I then entered my password (for the sudo), after which it downloads and installs PPTP support. To make sure Add button under VPN is now enabled, I also type the command:
sudo NetworkManager restart
Now, I simply click the network icon (from the top-right of the menu bar), click Configure VPN (under VPN Connections), I click the Add button, type in the IP address of the VPN server for the Gateway, my ActiveDirectory (from the Windows domain) username and password, followed by the domain name. I click the Advanced button and check the "Use Point-to-Point encryption (MPPE)" checkbox and click Ok on both dialog boxes.
To connect to the VPN, I click the network icon and under VPN Connections, I select the VPN connection that I just created.